Subategory:

Mutants

Description:

Using standard methods of directed mutagenesis and chloroplast transformation of rbcLΔ-MX3312 mt+ (MUT-4696), two substitutions (C256A and C369A) were created together in the Rubisco large subunit. Because Cys-256 and Cys-369 are methylated, this mutant was created to investigate the role of the modified residues in Rubisco structure or function. The C256A/C369A substitutions cause decreases in Rubisco CO₂/O₂ specificity and carboxylation catalytic efficiency. The mutant strain grows slowly on minimal medium at 25 °C, but dies on minimal medium at 35 °C. This strain has been maintained with acetate medium in darkness to prevent selection for secondary mutations that may improve Rubisco function.

Species:

Chlamydomonas

Locus:

rbcL

Chromosome:

Chloroplast

Phenotype:

Requires acetate at 35 °C; temperature-conditional